Permanent hydrocarbon reservoir monitoring is a technique where multiple three-dimensional seismic “pictures” of the state of a hydrocarbon reservoir are taken such that a geologist or reservoir engineer may plan the location of additional boreholes for increasing the efficiency of the hydrocarbon extraction and/or may assess the efficiency of the current extraction techniques over time. In some cases, taking multiple seismic pictures of a hydrocarbon reservoir may be referred to as four-dimensional (4D) seismic.
Marine-based permanent reservoir monitoring faces significant challenges that are not faced by land-based permanent monitoring systems. This is particularly true of ocean bottom installations as water depths extend into the 1000 meter range and beyond.